Photovoltaic devices are generally understood as photovoltaic cells or photovoltaic modules. Photovoltaic modules ordinarily comprise arrays of interconnected photovoltaic cells.
Thin-film photovoltaic modules, a variety of which is also known as thin-film solar modules, are generally composed of a number of electrically interconnected optoelectronic components. Such components may be optoelectronic devices such as photovoltaic cells and additional optional components such as diodes and other electronic devices.
Multilayer thin-film technologies enable the monolithic integration and interconnection of several optoelectronic components and associated components on a same substrate. This integration is produced in situ using a sequence of layer deposition and scribing techniques. Thin-film optoelectronic or photovoltaic components or devices are essentially composed of a stack of three material layers: a conducting back-contact electrode layer, a semiconductive photovoltaic material layer, also known as the absorber, and another conducting front-contact electrode layer, said front-contact layer usually being transparent. Photovoltaic cells based on semiconductive material such as Cu(In,Ga)Se2 (CIGS) or CdTe show promise for less expensive solar electricity, lower energy payback time, and improved life-cycle impact as compared to traditional wafer-based silicon photovoltaic devices or solar cells.
Compared to wafer-based photovoltaic devices, monolithic photovoltaic modules may have lower costs thanks to reduced material quantities used by thin films, reduced labor costs of monolithic integration, and ease of automatic production of large quantities of photovoltaic modules, for example using roll-to-roll manufacturing techniques. Further savings can be obtained by increasing the relative area of photovoltaic components exposed to light, for example by reducing the area occupied by front-contact grids that collect current over the photovoltaic cell's front-contact electrode, electrical interconnects between optoelectronic components, and busbars. Photovoltaic module production yields may also be increased thanks to a reduction in the number of production steps, for example by reducing or eliminating the step where front-contact grids are added.
Monolithic integration of series- or parallel-interconnected thin-film photovoltaic cells is a technology applied broadly in thin film photovoltaic module technology. U.S. patent application 2008/0314439 describes a process to form series-interconnected cells on an insulating substrate and using scribing operations, insulating ink, and conductive ink. Scribing is commonly done using mechanical or laser systems. U.S. patent application 2010/0065099 describes a different method to establish series interconnects that also uses scribing operations and the addition of resistive and conductive materials. U.S. patent application 2012/0234375 describes a glass-based, amorphous silicon thin-film solar module with a plurality of meandering grooves to establish electrical interconnects between cells. US 2012/0234375 presents a method and embodiments where meandering grooves may overlap when translated along one side of the substrate, i.e. the waves are spatially phase-aligned. Some embodiments in US 2012/0234375 present a smaller degree of bending of the waves from the center of the solar module toward the peripheral edges.